As a result of the steadily increasing cost of fossil fuels, the popularity of alternative energy sources has been steadily increasing.
One of these sources which is readily available is wind, and, indeed windmills have been used throughout the years to provide direct energy or energy which can be stored for later use.
Configurations for windmills have all suffered from disadvantages, however. Windmills which rotate vertically about a horizontal shaft tend to respond to directionally i.e. they are most efficient only when positioned in a certain orientation relative to the direction of the wind.
Windmill blades rotating horizontally about a vertical axis can be designed to eliminate this problem but these configurations are still susceptible to problems associated with wind force. High velocity wind flow tends to rotate the blades with sufficient force to tear the blade structure apart.
Also, sufficient wind force is necessary to cause rotation and low velocities tend to be unsuccessful in generating blade rotation.
Examples of blade configuration of the prior art can be found in U.S. Pat. Nos. 622,420; 603,703; 2,159,653; 2,419,384; 1,148,989 and 1,359,693.
U.S. Pat. No. 1,148,989 discloses a series of blades which are horizontally mounted and rotate vertically. These blades are positioned normal to the horizontal axis of the blade support and are generally triangular in configuration with a set of blades including an upper and a lower triangle. During rotation blades on one side of the axis are feathered into a central receiving area by complex mechanical means while the other blade set is operative.
U.S. Pat. No. 1,359,693 describes a pair of horizontally rotating blades formed as a section of a spiral. This patent discloses the concept of utilizing a bottom set of blades to catch wind spillage from an upper set of blades for increased efficiency.